Early gut microbiota linked to food sensitivities in infants

A study led by Hiroshi Ohno at the RIKEN Center for Integrative Medical Sciences (IMS) recently showed that certain gut bacteria found in one-month-old infants are associated with food sensitivities and the development of food allergies, particularly to eggs, while other types of bacteria are not. The study also found factors that predicted which type of bacteria would be present in the guts of newly born babies. Together, the findings suggest that certain probiotic supplements might be a good early defense for preventing food allergies, especially for at-risk infants. The study was published in the Journal of Allergy and Clinical Immunology.

Microbiota present in the gut soon after birth, which include bacteria, are known to help with normal development of the immune system and even protect against some diseases. However, research into the link between gut microbiota and food sensitivities and food allergies has produced mixed results. The new study tackled this problem by analyzing gut bacteria data from two separate groups of Japanese children for seven years, starting from birth. One was a high-risk group of 270 children from families with histories of allergies. The other was a group of 245 children from a previous study designed to test allergy treatments.

Food allergies happen when the body mistakes a protein in the food as dangerous and mounts an immune response to attack it. This immune response is in the form of the antibody called immunoglobulin E, or IgE for short, which comes in a number of varieties depending on the trouble-making food protein. The study looked at milk-, peanut-, egg white-, and wheat-specific IgE levels in the blood from one year after birth until the children were seven years old. At the same time, gut microbiota data were also collected, starting from one week after birth. By analyzing both, the team hoped to find predictable gut microbiota biomarkers for food sensitization and allergies.

The first finding was that of all the time points over the seven-year period, gut microbiota present one month after birth were the most related to the food-specific IgE levels in the blood, even when the children were seven years old. "We know that the early neonatal period is critical for immune system development," says Ohno, "and our results emphasize this, showing that the type of bacteria in the gut at this critical time is the best at predicting immune responses to food seven years down the road."

The analysis segregated microbiota into groups that changed over time. Focusing on the three types of bacteria that dominated the infant microbiomes one month after birth, the researchers found that babies with type-3, Bifidobacterium-dominant, microbiomes were significantly less likely to develop food sensitization to egg whites than were babies who had microbiomes that were dominated by one of the other categories of bacteria. This was also the trend for allergic reactions to egg whites later in life.

So, what determines which kind of bacteria an infant has one month after birth? To answer this question, researchers looked at other data available for the 515 children. They found that the type of delivery and the amount of breast feeding were linked to the gut microbiota. Infants who were delivered normally and received relatively less breast feeding turned out to be in the best shape, having type-3, Bifidobacterium-dominant microbiomes. Type-1 microbiota dominated when births were normal, but breast feeding was high, while type-2 microbiota dominated when delivery required a Cesarian section and the amount of breast feeding was low.

We conducted this study in the hope that a better understanding of neonatal gut microbiota would help generate ideas for allergy prevention strategies. We found that these microbiota do correlate with food allergens-specific serum IgE levels, and that intervention with Bifidobacterium during infancy might help prevent later food allergies, especially in infants who are the most at risk."

Hiroshi Ohno, RIKEN Center for Integrative Medical Sciences